|Do you know the source of the corruption?|
As far as recovery, you don't want to write anything to the pen drive. Doing so may overwrite anything you could recover intact or whole. Given your description it sounds like that is happening anyway.
You can try file scavenger, but if you do then just outright buy it. Your time would be limited by using the trial to test & see what you might recover before making the purchase, which is what you would have to do to recover anything it shows you. At least this is how it used to work. Although there is probably some truly free program out there I don't know of it. You will need an active internet connection for the license. Here is the link. Good Luck.
message edited by ISAmad